Development of liquid-phase oxidation processes by use of highly dispersed metal-metal oxide catalysts

使用高度分散的金属-金属氧化物催化剂开发液相氧化工艺

基本信息

批准号：
07555247
负责人：
TATSUMI Takashi
金额：
$ 5.82万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

We aimed at developing new catalyst systems which promote the partical oxidation of hydrocarbons. In the liquid phase conditions we have found that the size of the zeolite TS-1 crystals have a great influence on the activity of the catalyst because of the diffusion limitation of the reactants/products. The V-containing catalyst VS-2 was synthesized and proved to be active in the oxidation terminal carbons as well as internal carbons. By spin trapping experiments the formation of alkyl radical was detected for the alkane oxidation systems catalyzed by VS-2. The utilization of oxygen instead of H_2O_2 was attained by introducing metallic components incorporated inside the metallosilicates ; the catalyst seems to act as a bifunctional system. However, the rate of oxidation decreased with increasing temperature up to > 50ﾟC because of the promotion of the hydeogenolysis of H_2O_2. We have been successful in extending the system to gas phase oxidation. Methane was oxidized to formaldehyde over Pd/TS-1 in the presence of H_2 and O_2. Without addition of H_2 the complete oxidation occurred to give CO_2. Similar formaldehyde synthesis was also carried out over the mesoporous catalysts containing transition metals. Hydrothermally synthesized Mo-containing MCM-41 was found most selective for formaldehyde formation from methance and O_2. Vanadium-containing MCM-41 was active in the deep oxidation of methane. It is to be noted that the hydrothermally synthesized mesoporous metallosilicates were more selective than the mesoporous silicates impregnated with metal salts. The selectivity for formaldehyde was sharply dependent on the pore size of the zeolites/molecular sieves, which was interpreted in terms of the successive decomposition of once formed formaldehyde inside the relatively small pores.

我们旨在开发新的催化剂系统，以促进烃的特定氧化。在液相条件下，我们发现沸石TS-1晶体的大小对催化剂的活性有很大影响，因为反应物/产物的扩散限制。合成了含VS催化剂VS-2的VS-2，并证明在氧化末端碳和内部碳中具有活性。通过自旋诱捕实验，检测到烷基自由基的形成是通过VS-2催化的烷基氧化系统。氧气而不是H_2O_2的利用是通过引入金属硅酸盐中掺入的金属组件而入射的；该催化剂似乎是双功能系统。然而，由于促进了H_2O_2的氢化溶解，随着温度的增加，氧化速率随温度升高降低到> 50ﾟC的降低。我们已经成功地将系统扩展到气相氧化。在H_2和O_2存在下，将甲烷氧化以在PD/TS-1上甲醛。在不添加H_2的情况下，完全氧化会得到CO_2。在含有过渡金属的介孔催化剂上也进行了类似的甲醛合成。发现含甲醛和O_2的甲醛形成最有选择性的水热合成的MCM-41。含钒的MCM-41在甲烷的深氧化中活跃。值得注意的是，水热合成的介孔金属硅酸盐比用金属盐浸渍的介孔硅质更具选择性。甲醛的选择性急剧取决于沸石/分子筛子的孔径，这是根据曾经形成的甲醛在相对较小的毛孔内的成功分解来解释的。